The other night I had some lemon pepper chicken breast and asparagus, and I shit you not within 20 minutes of finishing my meal I took a leak that stunk like a skunk parboiled in sulphur...how does it get down there so fast?

Asparagus contains a high concentration of a sulfur-containing compound called asparagusic acid, named for the vegetable, of course, which can also be found in other pungent-smelling foods such as rotten eggs, onions and garlic. When your digestive system breaks down asparagusic acid, it releases volatile odoriferous components that are the culprits of the strange smell associated with asparagus urine. This process is so quick that the distinctive smell can develop within 15 to 30 minutes of eating asparagus, which can lead to unfortunate social circumstances such as awkward dinner-party bathroom breaks and avoidance of all beverages when asparagus is on the menu.

Asparagusic acid, as the name implies, is (to our knowledge) only found in asparagus. When our bodies digest the vegetable, they break down this chemical into a group of related sulfur-containing compounds with long, complicated names (including dimethyl sulfide, dimethyl disulfide, dimethyl sulfoxide and dimethyl sulfone). As with many other substances that include sulfur—such as garlic, skunk spray and odorized natural gas—these sulfur-containing molecules convey a powerful, typically unpleasant scent.

All of these molecules also share another key characteristic: They’re volatile, meaning that have a low enough boiling point that they can vaporize and enter a gaseous state at room temperature, which allows them to travel from urine into the air and up your nose. Asparagusic acid, on the other hand, isn’t volatile, so asparagus itself doesn’t convey the same rotten smell. But once your body converts asparagusic acid into these volatile, sulfur-bearing compounds, the distinctive aroma can be generated quite quickly—in some cases, it’s been detected in the urine of people who ate asparagus just 15-30 minutes earlier.